aboutsummaryrefslogtreecommitdiff
path: root/simd/jidctint-mmx.asm
blob: 5bd198120bddaba6984f9588401089d7080ee5a8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
;
; jidctint.asm - accurate integer IDCT (MMX)
;
; Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
;
; Based on the x86 SIMD extension for IJG JPEG library
; Copyright (C) 1999-2006, MIYASAKA Masaru.
; For conditions of distribution and use, see copyright notice in jsimdext.inc
;
; This file should be assembled with NASM (Netwide Assembler),
; can *not* be assembled with Microsoft's MASM or any compatible
; assembler (including Borland's Turbo Assembler).
; NASM is available from http://nasm.sourceforge.net/ or
; http://sourceforge.net/project/showfiles.php?group_id=6208
;
; This file contains a slow-but-accurate integer implementation of the
; inverse DCT (Discrete Cosine Transform). The following code is based
; directly on the IJG's original jidctint.c; see the jidctint.c for
; more details.
;
; [TAB8]

%include "jsimdext.inc"
%include "jdct.inc"

; --------------------------------------------------------------------------

%define CONST_BITS      13
%define PASS1_BITS      2

%define DESCALE_P1      (CONST_BITS-PASS1_BITS)
%define DESCALE_P2      (CONST_BITS+PASS1_BITS+3)

%if CONST_BITS == 13
F_0_298 equ      2446           ; FIX(0.298631336)
F_0_390 equ      3196           ; FIX(0.390180644)
F_0_541 equ      4433           ; FIX(0.541196100)
F_0_765 equ      6270           ; FIX(0.765366865)
F_0_899 equ      7373           ; FIX(0.899976223)
F_1_175 equ      9633           ; FIX(1.175875602)
F_1_501 equ     12299           ; FIX(1.501321110)
F_1_847 equ     15137           ; FIX(1.847759065)
F_1_961 equ     16069           ; FIX(1.961570560)
F_2_053 equ     16819           ; FIX(2.053119869)
F_2_562 equ     20995           ; FIX(2.562915447)
F_3_072 equ     25172           ; FIX(3.072711026)
%else
; NASM cannot do compile-time arithmetic on floating-point constants.
%define DESCALE(x,n)  (((x)+(1<<((n)-1)))>>(n))
F_0_298 equ     DESCALE( 320652955,30-CONST_BITS)       ; FIX(0.298631336)
F_0_390 equ     DESCALE( 418953276,30-CONST_BITS)       ; FIX(0.390180644)
F_0_541 equ     DESCALE( 581104887,30-CONST_BITS)       ; FIX(0.541196100)
F_0_765 equ     DESCALE( 821806413,30-CONST_BITS)       ; FIX(0.765366865)
F_0_899 equ     DESCALE( 966342111,30-CONST_BITS)       ; FIX(0.899976223)
F_1_175 equ     DESCALE(1262586813,30-CONST_BITS)       ; FIX(1.175875602)
F_1_501 equ     DESCALE(1612031267,30-CONST_BITS)       ; FIX(1.501321110)
F_1_847 equ     DESCALE(1984016188,30-CONST_BITS)       ; FIX(1.847759065)
F_1_961 equ     DESCALE(2106220350,30-CONST_BITS)       ; FIX(1.961570560)
F_2_053 equ     DESCALE(2204520673,30-CONST_BITS)       ; FIX(2.053119869)
F_2_562 equ     DESCALE(2751909506,30-CONST_BITS)       ; FIX(2.562915447)
F_3_072 equ     DESCALE(3299298341,30-CONST_BITS)       ; FIX(3.072711026)
%endif

; --------------------------------------------------------------------------
        SECTION SEG_CONST

        alignz  16
        global  EXTN(jconst_idct_islow_mmx)

EXTN(jconst_idct_islow_mmx):

PW_F130_F054    times 2 dw  (F_0_541+F_0_765), F_0_541
PW_F054_MF130   times 2 dw  F_0_541, (F_0_541-F_1_847)
PW_MF078_F117   times 2 dw  (F_1_175-F_1_961), F_1_175
PW_F117_F078    times 2 dw  F_1_175, (F_1_175-F_0_390)
PW_MF060_MF089  times 2 dw  (F_0_298-F_0_899),-F_0_899
PW_MF089_F060   times 2 dw -F_0_899, (F_1_501-F_0_899)
PW_MF050_MF256  times 2 dw  (F_2_053-F_2_562),-F_2_562
PW_MF256_F050   times 2 dw -F_2_562, (F_3_072-F_2_562)
PD_DESCALE_P1   times 2 dd  1 << (DESCALE_P1-1)
PD_DESCALE_P2   times 2 dd  1 << (DESCALE_P2-1)
PB_CENTERJSAMP  times 8 db  CENTERJSAMPLE

        alignz  16

; --------------------------------------------------------------------------
        SECTION SEG_TEXT
        BITS    32
;
; Perform dequantization and inverse DCT on one block of coefficients.
;
; GLOBAL(void)
; jsimd_idct_islow_mmx (void *dct_table, JCOEFPTR coef_block,
;                       JSAMPARRAY output_buf, JDIMENSION output_col)
;

%define dct_table(b)    (b)+8           ; jpeg_component_info *compptr
%define coef_block(b)   (b)+12          ; JCOEFPTR coef_block
%define output_buf(b)   (b)+16          ; JSAMPARRAY output_buf
%define output_col(b)   (b)+20          ; JDIMENSION output_col

%define original_ebp    ebp+0
%define wk(i)           ebp-(WK_NUM-(i))*SIZEOF_MMWORD  ; mmword wk[WK_NUM]
%define WK_NUM          12
%define workspace       wk(0)-DCTSIZE2*SIZEOF_JCOEF
                                        ; JCOEF workspace[DCTSIZE2]

        align   16
        global  EXTN(jsimd_idct_islow_mmx)

EXTN(jsimd_idct_islow_mmx):
        push    ebp
        mov     eax,esp                         ; eax = original ebp
        sub     esp, byte 4
        and     esp, byte (-SIZEOF_MMWORD)      ; align to 64 bits
        mov     [esp],eax
        mov     ebp,esp                         ; ebp = aligned ebp
        lea     esp, [workspace]
        push    ebx
;       push    ecx             ; need not be preserved
;       push    edx             ; need not be preserved
        push    esi
        push    edi

        get_GOT ebx             ; get GOT address

        ; ---- Pass 1: process columns from input, store into work array.

;       mov     eax, [original_ebp]
        mov     edx, POINTER [dct_table(eax)]           ; quantptr
        mov     esi, JCOEFPTR [coef_block(eax)]         ; inptr
        lea     edi, [workspace]                        ; JCOEF *wsptr
        mov     ecx, DCTSIZE/4                          ; ctr
        alignx  16,7
.columnloop:
%ifndef NO_ZERO_COLUMN_TEST_ISLOW_MMX
        mov     eax, DWORD [DWBLOCK(1,0,esi,SIZEOF_JCOEF)]
        or      eax, DWORD [DWBLOCK(2,0,esi,SIZEOF_JCOEF)]
        jnz     short .columnDCT

        movq    mm0, MMWORD [MMBLOCK(1,0,esi,SIZEOF_JCOEF)]
        movq    mm1, MMWORD [MMBLOCK(2,0,esi,SIZEOF_JCOEF)]
        por     mm0, MMWORD [MMBLOCK(3,0,esi,SIZEOF_JCOEF)]
        por     mm1, MMWORD [MMBLOCK(4,0,esi,SIZEOF_JCOEF)]
        por     mm0, MMWORD [MMBLOCK(5,0,esi,SIZEOF_JCOEF)]
        por     mm1, MMWORD [MMBLOCK(6,0,esi,SIZEOF_JCOEF)]
        por     mm0, MMWORD [MMBLOCK(7,0,esi,SIZEOF_JCOEF)]
        por     mm1,mm0
        packsswb mm1,mm1
        movd    eax,mm1
        test    eax,eax
        jnz     short .columnDCT

        ; -- AC terms all zero

        movq    mm0, MMWORD [MMBLOCK(0,0,esi,SIZEOF_JCOEF)]
        pmullw  mm0, MMWORD [MMBLOCK(0,0,edx,SIZEOF_ISLOW_MULT_TYPE)]

        psllw   mm0,PASS1_BITS

        movq      mm2,mm0               ; mm0=in0=(00 01 02 03)
        punpcklwd mm0,mm0               ; mm0=(00 00 01 01)
        punpckhwd mm2,mm2               ; mm2=(02 02 03 03)

        movq      mm1,mm0
        punpckldq mm0,mm0               ; mm0=(00 00 00 00)
        punpckhdq mm1,mm1               ; mm1=(01 01 01 01)
        movq      mm3,mm2
        punpckldq mm2,mm2               ; mm2=(02 02 02 02)
        punpckhdq mm3,mm3               ; mm3=(03 03 03 03)

        movq    MMWORD [MMBLOCK(0,0,edi,SIZEOF_JCOEF)], mm0
        movq    MMWORD [MMBLOCK(0,1,edi,SIZEOF_JCOEF)], mm0
        movq    MMWORD [MMBLOCK(1,0,edi,SIZEOF_JCOEF)], mm1
        movq    MMWORD [MMBLOCK(1,1,edi,SIZEOF_JCOEF)], mm1
        movq    MMWORD [MMBLOCK(2,0,edi,SIZEOF_JCOEF)], mm2
        movq    MMWORD [MMBLOCK(2,1,edi,SIZEOF_JCOEF)], mm2
        movq    MMWORD [MMBLOCK(3,0,edi,SIZEOF_JCOEF)], mm3
        movq    MMWORD [MMBLOCK(3,1,edi,SIZEOF_JCOEF)], mm3
        jmp     near .nextcolumn
        alignx  16,7
%endif
.columnDCT:

        ; -- Even part

        movq    mm0, MMWORD [MMBLOCK(0,0,esi,SIZEOF_JCOEF)]
        movq    mm1, MMWORD [MMBLOCK(2,0,esi,SIZEOF_JCOEF)]
        pmullw  mm0, MMWORD [MMBLOCK(0,0,edx,SIZEOF_ISLOW_MULT_TYPE)]
        pmullw  mm1, MMWORD [MMBLOCK(2,0,edx,SIZEOF_ISLOW_MULT_TYPE)]
        movq    mm2, MMWORD [MMBLOCK(4,0,esi,SIZEOF_JCOEF)]
        movq    mm3, MMWORD [MMBLOCK(6,0,esi,SIZEOF_JCOEF)]
        pmullw  mm2, MMWORD [MMBLOCK(4,0,edx,SIZEOF_ISLOW_MULT_TYPE)]
        pmullw  mm3, MMWORD [MMBLOCK(6,0,edx,SIZEOF_ISLOW_MULT_TYPE)]

        ; (Original)
        ; z1 = (z2 + z3) * 0.541196100;
        ; tmp2 = z1 + z3 * -1.847759065;
        ; tmp3 = z1 + z2 * 0.765366865;
        ;
        ; (This implementation)
        ; tmp2 = z2 * 0.541196100 + z3 * (0.541196100 - 1.847759065);
        ; tmp3 = z2 * (0.541196100 + 0.765366865) + z3 * 0.541196100;

        movq      mm4,mm1               ; mm1=in2=z2
        movq      mm5,mm1
        punpcklwd mm4,mm3               ; mm3=in6=z3
        punpckhwd mm5,mm3
        movq      mm1,mm4
        movq      mm3,mm5
        pmaddwd   mm4,[GOTOFF(ebx,PW_F130_F054)]        ; mm4=tmp3L
        pmaddwd   mm5,[GOTOFF(ebx,PW_F130_F054)]        ; mm5=tmp3H
        pmaddwd   mm1,[GOTOFF(ebx,PW_F054_MF130)]       ; mm1=tmp2L
        pmaddwd   mm3,[GOTOFF(ebx,PW_F054_MF130)]       ; mm3=tmp2H

        movq      mm6,mm0
        paddw     mm0,mm2               ; mm0=in0+in4
        psubw     mm6,mm2               ; mm6=in0-in4

        pxor      mm7,mm7
        pxor      mm2,mm2
        punpcklwd mm7,mm0               ; mm7=tmp0L
        punpckhwd mm2,mm0               ; mm2=tmp0H
        psrad     mm7,(16-CONST_BITS)   ; psrad mm7,16 & pslld mm7,CONST_BITS
        psrad     mm2,(16-CONST_BITS)   ; psrad mm2,16 & pslld mm2,CONST_BITS

        movq    mm0,mm7
        paddd   mm7,mm4                 ; mm7=tmp10L
        psubd   mm0,mm4                 ; mm0=tmp13L
        movq    mm4,mm2
        paddd   mm2,mm5                 ; mm2=tmp10H
        psubd   mm4,mm5                 ; mm4=tmp13H

        movq    MMWORD [wk(0)], mm7     ; wk(0)=tmp10L
        movq    MMWORD [wk(1)], mm2     ; wk(1)=tmp10H
        movq    MMWORD [wk(2)], mm0     ; wk(2)=tmp13L
        movq    MMWORD [wk(3)], mm4     ; wk(3)=tmp13H

        pxor      mm5,mm5
        pxor      mm7,mm7
        punpcklwd mm5,mm6               ; mm5=tmp1L
        punpckhwd mm7,mm6               ; mm7=tmp1H
        psrad     mm5,(16-CONST_BITS)   ; psrad mm5,16 & pslld mm5,CONST_BITS
        psrad     mm7,(16-CONST_BITS)   ; psrad mm7,16 & pslld mm7,CONST_BITS

        movq    mm2,mm5
        paddd   mm5,mm1                 ; mm5=tmp11L
        psubd   mm2,mm1                 ; mm2=tmp12L
        movq    mm0,mm7
        paddd   mm7,mm3                 ; mm7=tmp11H
        psubd   mm0,mm3                 ; mm0=tmp12H

        movq    MMWORD [wk(4)], mm5     ; wk(4)=tmp11L
        movq    MMWORD [wk(5)], mm7     ; wk(5)=tmp11H
        movq    MMWORD [wk(6)], mm2     ; wk(6)=tmp12L
        movq    MMWORD [wk(7)], mm0     ; wk(7)=tmp12H

        ; -- Odd part

        movq    mm4, MMWORD [MMBLOCK(1,0,esi,SIZEOF_JCOEF)]
        movq    mm6, MMWORD [MMBLOCK(3,0,esi,SIZEOF_JCOEF)]
        pmullw  mm4, MMWORD [MMBLOCK(1,0,edx,SIZEOF_ISLOW_MULT_TYPE)]
        pmullw  mm6, MMWORD [MMBLOCK(3,0,edx,SIZEOF_ISLOW_MULT_TYPE)]
        movq    mm1, MMWORD [MMBLOCK(5,0,esi,SIZEOF_JCOEF)]
        movq    mm3, MMWORD [MMBLOCK(7,0,esi,SIZEOF_JCOEF)]
        pmullw  mm1, MMWORD [MMBLOCK(5,0,edx,SIZEOF_ISLOW_MULT_TYPE)]
        pmullw  mm3, MMWORD [MMBLOCK(7,0,edx,SIZEOF_ISLOW_MULT_TYPE)]

        movq    mm5,mm6
        movq    mm7,mm4
        paddw   mm5,mm3                 ; mm5=z3
        paddw   mm7,mm1                 ; mm7=z4

        ; (Original)
        ; z5 = (z3 + z4) * 1.175875602;
        ; z3 = z3 * -1.961570560;  z4 = z4 * -0.390180644;
        ; z3 += z5;  z4 += z5;
        ;
        ; (This implementation)
        ; z3 = z3 * (1.175875602 - 1.961570560) + z4 * 1.175875602;
        ; z4 = z3 * 1.175875602 + z4 * (1.175875602 - 0.390180644);

        movq      mm2,mm5
        movq      mm0,mm5
        punpcklwd mm2,mm7
        punpckhwd mm0,mm7
        movq      mm5,mm2
        movq      mm7,mm0
        pmaddwd   mm2,[GOTOFF(ebx,PW_MF078_F117)]       ; mm2=z3L
        pmaddwd   mm0,[GOTOFF(ebx,PW_MF078_F117)]       ; mm0=z3H
        pmaddwd   mm5,[GOTOFF(ebx,PW_F117_F078)]        ; mm5=z4L
        pmaddwd   mm7,[GOTOFF(ebx,PW_F117_F078)]        ; mm7=z4H

        movq    MMWORD [wk(10)], mm2    ; wk(10)=z3L
        movq    MMWORD [wk(11)], mm0    ; wk(11)=z3H

        ; (Original)
        ; z1 = tmp0 + tmp3;  z2 = tmp1 + tmp2;
        ; tmp0 = tmp0 * 0.298631336;  tmp1 = tmp1 * 2.053119869;
        ; tmp2 = tmp2 * 3.072711026;  tmp3 = tmp3 * 1.501321110;
        ; z1 = z1 * -0.899976223;  z2 = z2 * -2.562915447;
        ; tmp0 += z1 + z3;  tmp1 += z2 + z4;
        ; tmp2 += z2 + z3;  tmp3 += z1 + z4;
        ;
        ; (This implementation)
        ; tmp0 = tmp0 * (0.298631336 - 0.899976223) + tmp3 * -0.899976223;
        ; tmp1 = tmp1 * (2.053119869 - 2.562915447) + tmp2 * -2.562915447;
        ; tmp2 = tmp1 * -2.562915447 + tmp2 * (3.072711026 - 2.562915447);
        ; tmp3 = tmp0 * -0.899976223 + tmp3 * (1.501321110 - 0.899976223);
        ; tmp0 += z3;  tmp1 += z4;
        ; tmp2 += z3;  tmp3 += z4;

        movq      mm2,mm3
        movq      mm0,mm3
        punpcklwd mm2,mm4
        punpckhwd mm0,mm4
        movq      mm3,mm2
        movq      mm4,mm0
        pmaddwd   mm2,[GOTOFF(ebx,PW_MF060_MF089)]      ; mm2=tmp0L
        pmaddwd   mm0,[GOTOFF(ebx,PW_MF060_MF089)]      ; mm0=tmp0H
        pmaddwd   mm3,[GOTOFF(ebx,PW_MF089_F060)]       ; mm3=tmp3L
        pmaddwd   mm4,[GOTOFF(ebx,PW_MF089_F060)]       ; mm4=tmp3H

        paddd   mm2, MMWORD [wk(10)]    ; mm2=tmp0L
        paddd   mm0, MMWORD [wk(11)]    ; mm0=tmp0H
        paddd   mm3,mm5                 ; mm3=tmp3L
        paddd   mm4,mm7                 ; mm4=tmp3H

        movq    MMWORD [wk(8)], mm2     ; wk(8)=tmp0L
        movq    MMWORD [wk(9)], mm0     ; wk(9)=tmp0H

        movq      mm2,mm1
        movq      mm0,mm1
        punpcklwd mm2,mm6
        punpckhwd mm0,mm6
        movq      mm1,mm2
        movq      mm6,mm0
        pmaddwd   mm2,[GOTOFF(ebx,PW_MF050_MF256)]      ; mm2=tmp1L
        pmaddwd   mm0,[GOTOFF(ebx,PW_MF050_MF256)]      ; mm0=tmp1H
        pmaddwd   mm1,[GOTOFF(ebx,PW_MF256_F050)]       ; mm1=tmp2L
        pmaddwd   mm6,[GOTOFF(ebx,PW_MF256_F050)]       ; mm6=tmp2H

        paddd   mm2,mm5                 ; mm2=tmp1L
        paddd   mm0,mm7                 ; mm0=tmp1H
        paddd   mm1, MMWORD [wk(10)]    ; mm1=tmp2L
        paddd   mm6, MMWORD [wk(11)]    ; mm6=tmp2H

        movq    MMWORD [wk(10)], mm2    ; wk(10)=tmp1L
        movq    MMWORD [wk(11)], mm0    ; wk(11)=tmp1H

        ; -- Final output stage

        movq    mm5, MMWORD [wk(0)]     ; mm5=tmp10L
        movq    mm7, MMWORD [wk(1)]     ; mm7=tmp10H

        movq    mm2,mm5
        movq    mm0,mm7
        paddd   mm5,mm3                 ; mm5=data0L
        paddd   mm7,mm4                 ; mm7=data0H
        psubd   mm2,mm3                 ; mm2=data7L
        psubd   mm0,mm4                 ; mm0=data7H

        movq    mm3,[GOTOFF(ebx,PD_DESCALE_P1)] ; mm3=[PD_DESCALE_P1]

        paddd   mm5,mm3
        paddd   mm7,mm3
        psrad   mm5,DESCALE_P1
        psrad   mm7,DESCALE_P1
        paddd   mm2,mm3
        paddd   mm0,mm3
        psrad   mm2,DESCALE_P1
        psrad   mm0,DESCALE_P1

        packssdw  mm5,mm7               ; mm5=data0=(00 01 02 03)
        packssdw  mm2,mm0               ; mm2=data7=(70 71 72 73)

        movq    mm4, MMWORD [wk(4)]     ; mm4=tmp11L
        movq    mm3, MMWORD [wk(5)]     ; mm3=tmp11H

        movq    mm7,mm4
        movq    mm0,mm3
        paddd   mm4,mm1                 ; mm4=data1L
        paddd   mm3,mm6                 ; mm3=data1H
        psubd   mm7,mm1                 ; mm7=data6L
        psubd   mm0,mm6                 ; mm0=data6H

        movq    mm1,[GOTOFF(ebx,PD_DESCALE_P1)] ; mm1=[PD_DESCALE_P1]

        paddd   mm4,mm1
        paddd   mm3,mm1
        psrad   mm4,DESCALE_P1
        psrad   mm3,DESCALE_P1
        paddd   mm7,mm1
        paddd   mm0,mm1
        psrad   mm7,DESCALE_P1
        psrad   mm0,DESCALE_P1

        packssdw  mm4,mm3               ; mm4=data1=(10 11 12 13)
        packssdw  mm7,mm0               ; mm7=data6=(60 61 62 63)

        movq      mm6,mm5               ; transpose coefficients(phase 1)
        punpcklwd mm5,mm4               ; mm5=(00 10 01 11)
        punpckhwd mm6,mm4               ; mm6=(02 12 03 13)
        movq      mm1,mm7               ; transpose coefficients(phase 1)
        punpcklwd mm7,mm2               ; mm7=(60 70 61 71)
        punpckhwd mm1,mm2               ; mm1=(62 72 63 73)

        movq    mm3, MMWORD [wk(6)]     ; mm3=tmp12L
        movq    mm0, MMWORD [wk(7)]     ; mm0=tmp12H
        movq    mm4, MMWORD [wk(10)]    ; mm4=tmp1L
        movq    mm2, MMWORD [wk(11)]    ; mm2=tmp1H

        movq    MMWORD [wk(0)], mm5     ; wk(0)=(00 10 01 11)
        movq    MMWORD [wk(1)], mm6     ; wk(1)=(02 12 03 13)
        movq    MMWORD [wk(4)], mm7     ; wk(4)=(60 70 61 71)
        movq    MMWORD [wk(5)], mm1     ; wk(5)=(62 72 63 73)

        movq    mm5,mm3
        movq    mm6,mm0
        paddd   mm3,mm4                 ; mm3=data2L
        paddd   mm0,mm2                 ; mm0=data2H
        psubd   mm5,mm4                 ; mm5=data5L
        psubd   mm6,mm2                 ; mm6=data5H

        movq    mm7,[GOTOFF(ebx,PD_DESCALE_P1)] ; mm7=[PD_DESCALE_P1]

        paddd   mm3,mm7
        paddd   mm0,mm7
        psrad   mm3,DESCALE_P1
        psrad   mm0,DESCALE_P1
        paddd   mm5,mm7
        paddd   mm6,mm7
        psrad   mm5,DESCALE_P1
        psrad   mm6,DESCALE_P1

        packssdw  mm3,mm0               ; mm3=data2=(20 21 22 23)
        packssdw  mm5,mm6               ; mm5=data5=(50 51 52 53)

        movq    mm1, MMWORD [wk(2)]     ; mm1=tmp13L
        movq    mm4, MMWORD [wk(3)]     ; mm4=tmp13H
        movq    mm2, MMWORD [wk(8)]     ; mm2=tmp0L
        movq    mm7, MMWORD [wk(9)]     ; mm7=tmp0H

        movq    mm0,mm1
        movq    mm6,mm4
        paddd   mm1,mm2                 ; mm1=data3L
        paddd   mm4,mm7                 ; mm4=data3H
        psubd   mm0,mm2                 ; mm0=data4L
        psubd   mm6,mm7                 ; mm6=data4H

        movq    mm2,[GOTOFF(ebx,PD_DESCALE_P1)] ; mm2=[PD_DESCALE_P1]

        paddd   mm1,mm2
        paddd   mm4,mm2
        psrad   mm1,DESCALE_P1
        psrad   mm4,DESCALE_P1
        paddd   mm0,mm2
        paddd   mm6,mm2
        psrad   mm0,DESCALE_P1
        psrad   mm6,DESCALE_P1

        packssdw  mm1,mm4               ; mm1=data3=(30 31 32 33)
        packssdw  mm0,mm6               ; mm0=data4=(40 41 42 43)

        movq    mm7, MMWORD [wk(0)]     ; mm7=(00 10 01 11)
        movq    mm2, MMWORD [wk(1)]     ; mm2=(02 12 03 13)

        movq      mm4,mm3               ; transpose coefficients(phase 1)
        punpcklwd mm3,mm1               ; mm3=(20 30 21 31)
        punpckhwd mm4,mm1               ; mm4=(22 32 23 33)
        movq      mm6,mm0               ; transpose coefficients(phase 1)
        punpcklwd mm0,mm5               ; mm0=(40 50 41 51)
        punpckhwd mm6,mm5               ; mm6=(42 52 43 53)

        movq      mm1,mm7               ; transpose coefficients(phase 2)
        punpckldq mm7,mm3               ; mm7=(00 10 20 30)
        punpckhdq mm1,mm3               ; mm1=(01 11 21 31)
        movq      mm5,mm2               ; transpose coefficients(phase 2)
        punpckldq mm2,mm4               ; mm2=(02 12 22 32)
        punpckhdq mm5,mm4               ; mm5=(03 13 23 33)

        movq    mm3, MMWORD [wk(4)]     ; mm3=(60 70 61 71)
        movq    mm4, MMWORD [wk(5)]     ; mm4=(62 72 63 73)

        movq    MMWORD [MMBLOCK(0,0,edi,SIZEOF_JCOEF)], mm7
        movq    MMWORD [MMBLOCK(1,0,edi,SIZEOF_JCOEF)], mm1
        movq    MMWORD [MMBLOCK(2,0,edi,SIZEOF_JCOEF)], mm2
        movq    MMWORD [MMBLOCK(3,0,edi,SIZEOF_JCOEF)], mm5

        movq      mm7,mm0               ; transpose coefficients(phase 2)
        punpckldq mm0,mm3               ; mm0=(40 50 60 70)
        punpckhdq mm7,mm3               ; mm7=(41 51 61 71)
        movq      mm1,mm6               ; transpose coefficients(phase 2)
        punpckldq mm6,mm4               ; mm6=(42 52 62 72)
        punpckhdq mm1,mm4               ; mm1=(43 53 63 73)

        movq    MMWORD [MMBLOCK(0,1,edi,SIZEOF_JCOEF)], mm0
        movq    MMWORD [MMBLOCK(1,1,edi,SIZEOF_JCOEF)], mm7
        movq    MMWORD [MMBLOCK(2,1,edi,SIZEOF_JCOEF)], mm6
        movq    MMWORD [MMBLOCK(3,1,edi,SIZEOF_JCOEF)], mm1

.nextcolumn:
        add     esi, byte 4*SIZEOF_JCOEF                ; coef_block
        add     edx, byte 4*SIZEOF_ISLOW_MULT_TYPE      ; quantptr
        add     edi, byte 4*DCTSIZE*SIZEOF_JCOEF        ; wsptr
        dec     ecx                                     ; ctr
        jnz     near .columnloop

        ; ---- Pass 2: process rows from work array, store into output array.

        mov     eax, [original_ebp]
        lea     esi, [workspace]                        ; JCOEF *wsptr
        mov     edi, JSAMPARRAY [output_buf(eax)]       ; (JSAMPROW *)
        mov     eax, JDIMENSION [output_col(eax)]
        mov     ecx, DCTSIZE/4                          ; ctr
        alignx  16,7
.rowloop:

        ; -- Even part

        movq    mm0, MMWORD [MMBLOCK(0,0,esi,SIZEOF_JCOEF)]
        movq    mm1, MMWORD [MMBLOCK(2,0,esi,SIZEOF_JCOEF)]
        movq    mm2, MMWORD [MMBLOCK(4,0,esi,SIZEOF_JCOEF)]
        movq    mm3, MMWORD [MMBLOCK(6,0,esi,SIZEOF_JCOEF)]

        ; (Original)
        ; z1 = (z2 + z3) * 0.541196100;
        ; tmp2 = z1 + z3 * -1.847759065;
        ; tmp3 = z1 + z2 * 0.765366865;
        ;
        ; (This implementation)
        ; tmp2 = z2 * 0.541196100 + z3 * (0.541196100 - 1.847759065);
        ; tmp3 = z2 * (0.541196100 + 0.765366865) + z3 * 0.541196100;

        movq      mm4,mm1               ; mm1=in2=z2
        movq      mm5,mm1
        punpcklwd mm4,mm3               ; mm3=in6=z3
        punpckhwd mm5,mm3
        movq      mm1,mm4
        movq      mm3,mm5
        pmaddwd   mm4,[GOTOFF(ebx,PW_F130_F054)]        ; mm4=tmp3L
        pmaddwd   mm5,[GOTOFF(ebx,PW_F130_F054)]        ; mm5=tmp3H
        pmaddwd   mm1,[GOTOFF(ebx,PW_F054_MF130)]       ; mm1=tmp2L
        pmaddwd   mm3,[GOTOFF(ebx,PW_F054_MF130)]       ; mm3=tmp2H

        movq      mm6,mm0
        paddw     mm0,mm2               ; mm0=in0+in4
        psubw     mm6,mm2               ; mm6=in0-in4

        pxor      mm7,mm7
        pxor      mm2,mm2
        punpcklwd mm7,mm0               ; mm7=tmp0L
        punpckhwd mm2,mm0               ; mm2=tmp0H
        psrad     mm7,(16-CONST_BITS)   ; psrad mm7,16 & pslld mm7,CONST_BITS
        psrad     mm2,(16-CONST_BITS)   ; psrad mm2,16 & pslld mm2,CONST_BITS

        movq    mm0,mm7
        paddd   mm7,mm4                 ; mm7=tmp10L
        psubd   mm0,mm4                 ; mm0=tmp13L
        movq    mm4,mm2
        paddd   mm2,mm5                 ; mm2=tmp10H
        psubd   mm4,mm5                 ; mm4=tmp13H

        movq    MMWORD [wk(0)], mm7     ; wk(0)=tmp10L
        movq    MMWORD [wk(1)], mm2     ; wk(1)=tmp10H
        movq    MMWORD [wk(2)], mm0     ; wk(2)=tmp13L
        movq    MMWORD [wk(3)], mm4     ; wk(3)=tmp13H

        pxor      mm5,mm5
        pxor      mm7,mm7
        punpcklwd mm5,mm6               ; mm5=tmp1L
        punpckhwd mm7,mm6               ; mm7=tmp1H
        psrad     mm5,(16-CONST_BITS)   ; psrad mm5,16 & pslld mm5,CONST_BITS
        psrad     mm7,(16-CONST_BITS)   ; psrad mm7,16 & pslld mm7,CONST_BITS

        movq    mm2,mm5
        paddd   mm5,mm1                 ; mm5=tmp11L
        psubd   mm2,mm1                 ; mm2=tmp12L
        movq    mm0,mm7
        paddd   mm7,mm3                 ; mm7=tmp11H
        psubd   mm0,mm3                 ; mm0=tmp12H

        movq    MMWORD [wk(4)], mm5     ; wk(4)=tmp11L
        movq    MMWORD [wk(5)], mm7     ; wk(5)=tmp11H
        movq    MMWORD [wk(6)], mm2     ; wk(6)=tmp12L
        movq    MMWORD [wk(7)], mm0     ; wk(7)=tmp12H

        ; -- Odd part

        movq    mm4, MMWORD [MMBLOCK(1,0,esi,SIZEOF_JCOEF)]
        movq    mm6, MMWORD [MMBLOCK(3,0,esi,SIZEOF_JCOEF)]
        movq    mm1, MMWORD [MMBLOCK(5,0,esi,SIZEOF_JCOEF)]
        movq    mm3, MMWORD [MMBLOCK(7,0,esi,SIZEOF_JCOEF)]

        movq    mm5,mm6
        movq    mm7,mm4
        paddw   mm5,mm3                 ; mm5=z3
        paddw   mm7,mm1                 ; mm7=z4

        ; (Original)
        ; z5 = (z3 + z4) * 1.175875602;
        ; z3 = z3 * -1.961570560;  z4 = z4 * -0.390180644;
        ; z3 += z5;  z4 += z5;
        ;
        ; (This implementation)
        ; z3 = z3 * (1.175875602 - 1.961570560) + z4 * 1.175875602;
        ; z4 = z3 * 1.175875602 + z4 * (1.175875602 - 0.390180644);

        movq      mm2,mm5
        movq      mm0,mm5
        punpcklwd mm2,mm7
        punpckhwd mm0,mm7
        movq      mm5,mm2
        movq      mm7,mm0
        pmaddwd   mm2,[GOTOFF(ebx,PW_MF078_F117)]       ; mm2=z3L
        pmaddwd   mm0,[GOTOFF(ebx,PW_MF078_F117)]       ; mm0=z3H
        pmaddwd   mm5,[GOTOFF(ebx,PW_F117_F078)]        ; mm5=z4L
        pmaddwd   mm7,[GOTOFF(ebx,PW_F117_F078)]        ; mm7=z4H

        movq    MMWORD [wk(10)], mm2    ; wk(10)=z3L
        movq    MMWORD [wk(11)], mm0    ; wk(11)=z3H

        ; (Original)
        ; z1 = tmp0 + tmp3;  z2 = tmp1 + tmp2;
        ; tmp0 = tmp0 * 0.298631336;  tmp1 = tmp1 * 2.053119869;
        ; tmp2 = tmp2 * 3.072711026;  tmp3 = tmp3 * 1.501321110;
        ; z1 = z1 * -0.899976223;  z2 = z2 * -2.562915447;
        ; tmp0 += z1 + z3;  tmp1 += z2 + z4;
        ; tmp2 += z2 + z3;  tmp3 += z1 + z4;
        ;
        ; (This implementation)
        ; tmp0 = tmp0 * (0.298631336 - 0.899976223) + tmp3 * -0.899976223;
        ; tmp1 = tmp1 * (2.053119869 - 2.562915447) + tmp2 * -2.562915447;
        ; tmp2 = tmp1 * -2.562915447 + tmp2 * (3.072711026 - 2.562915447);
        ; tmp3 = tmp0 * -0.899976223 + tmp3 * (1.501321110 - 0.899976223);
        ; tmp0 += z3;  tmp1 += z4;
        ; tmp2 += z3;  tmp3 += z4;

        movq      mm2,mm3
        movq      mm0,mm3
        punpcklwd mm2,mm4
        punpckhwd mm0,mm4
        movq      mm3,mm2
        movq      mm4,mm0
        pmaddwd   mm2,[GOTOFF(ebx,PW_MF060_MF089)]      ; mm2=tmp0L
        pmaddwd   mm0,[GOTOFF(ebx,PW_MF060_MF089)]      ; mm0=tmp0H
        pmaddwd   mm3,[GOTOFF(ebx,PW_MF089_F060)]       ; mm3=tmp3L
        pmaddwd   mm4,[GOTOFF(ebx,PW_MF089_F060)]       ; mm4=tmp3H

        paddd   mm2, MMWORD [wk(10)]    ; mm2=tmp0L
        paddd   mm0, MMWORD [wk(11)]    ; mm0=tmp0H
        paddd   mm3,mm5                 ; mm3=tmp3L
        paddd   mm4,mm7                 ; mm4=tmp3H

        movq    MMWORD [wk(8)], mm2     ; wk(8)=tmp0L
        movq    MMWORD [wk(9)], mm0     ; wk(9)=tmp0H

        movq      mm2,mm1
        movq      mm0,mm1
        punpcklwd mm2,mm6
        punpckhwd mm0,mm6
        movq      mm1,mm2
        movq      mm6,mm0
        pmaddwd   mm2,[GOTOFF(ebx,PW_MF050_MF256)]      ; mm2=tmp1L
        pmaddwd   mm0,[GOTOFF(ebx,PW_MF050_MF256)]      ; mm0=tmp1H
        pmaddwd   mm1,[GOTOFF(ebx,PW_MF256_F050)]       ; mm1=tmp2L
        pmaddwd   mm6,[GOTOFF(ebx,PW_MF256_F050)]       ; mm6=tmp2H

        paddd   mm2,mm5                 ; mm2=tmp1L
        paddd   mm0,mm7                 ; mm0=tmp1H
        paddd   mm1, MMWORD [wk(10)]    ; mm1=tmp2L
        paddd   mm6, MMWORD [wk(11)]    ; mm6=tmp2H

        movq    MMWORD [wk(10)], mm2    ; wk(10)=tmp1L
        movq    MMWORD [wk(11)], mm0    ; wk(11)=tmp1H

        ; -- Final output stage

        movq    mm5, MMWORD [wk(0)]     ; mm5=tmp10L
        movq    mm7, MMWORD [wk(1)]     ; mm7=tmp10H

        movq    mm2,mm5
        movq    mm0,mm7
        paddd   mm5,mm3                 ; mm5=data0L
        paddd   mm7,mm4                 ; mm7=data0H
        psubd   mm2,mm3                 ; mm2=data7L
        psubd   mm0,mm4                 ; mm0=data7H

        movq    mm3,[GOTOFF(ebx,PD_DESCALE_P2)] ; mm3=[PD_DESCALE_P2]

        paddd   mm5,mm3
        paddd   mm7,mm3
        psrad   mm5,DESCALE_P2
        psrad   mm7,DESCALE_P2
        paddd   mm2,mm3
        paddd   mm0,mm3
        psrad   mm2,DESCALE_P2
        psrad   mm0,DESCALE_P2

        packssdw  mm5,mm7               ; mm5=data0=(00 10 20 30)
        packssdw  mm2,mm0               ; mm2=data7=(07 17 27 37)

        movq    mm4, MMWORD [wk(4)]     ; mm4=tmp11L
        movq    mm3, MMWORD [wk(5)]     ; mm3=tmp11H

        movq    mm7,mm4
        movq    mm0,mm3
        paddd   mm4,mm1                 ; mm4=data1L
        paddd   mm3,mm6                 ; mm3=data1H
        psubd   mm7,mm1                 ; mm7=data6L
        psubd   mm0,mm6                 ; mm0=data6H

        movq    mm1,[GOTOFF(ebx,PD_DESCALE_P2)] ; mm1=[PD_DESCALE_P2]

        paddd   mm4,mm1
        paddd   mm3,mm1
        psrad   mm4,DESCALE_P2
        psrad   mm3,DESCALE_P2
        paddd   mm7,mm1
        paddd   mm0,mm1
        psrad   mm7,DESCALE_P2
        psrad   mm0,DESCALE_P2

        packssdw  mm4,mm3               ; mm4=data1=(01 11 21 31)
        packssdw  mm7,mm0               ; mm7=data6=(06 16 26 36)

        packsswb  mm5,mm7               ; mm5=(00 10 20 30 06 16 26 36)
        packsswb  mm4,mm2               ; mm4=(01 11 21 31 07 17 27 37)

        movq    mm6, MMWORD [wk(6)]     ; mm6=tmp12L
        movq    mm1, MMWORD [wk(7)]     ; mm1=tmp12H
        movq    mm3, MMWORD [wk(10)]    ; mm3=tmp1L
        movq    mm0, MMWORD [wk(11)]    ; mm0=tmp1H

        movq    MMWORD [wk(0)], mm5     ; wk(0)=(00 10 20 30 06 16 26 36)
        movq    MMWORD [wk(1)], mm4     ; wk(1)=(01 11 21 31 07 17 27 37)

        movq    mm7,mm6
        movq    mm2,mm1
        paddd   mm6,mm3                 ; mm6=data2L
        paddd   mm1,mm0                 ; mm1=data2H
        psubd   mm7,mm3                 ; mm7=data5L
        psubd   mm2,mm0                 ; mm2=data5H

        movq    mm5,[GOTOFF(ebx,PD_DESCALE_P2)] ; mm5=[PD_DESCALE_P2]

        paddd   mm6,mm5
        paddd   mm1,mm5
        psrad   mm6,DESCALE_P2
        psrad   mm1,DESCALE_P2
        paddd   mm7,mm5
        paddd   mm2,mm5
        psrad   mm7,DESCALE_P2
        psrad   mm2,DESCALE_P2

        packssdw  mm6,mm1               ; mm6=data2=(02 12 22 32)
        packssdw  mm7,mm2               ; mm7=data5=(05 15 25 35)

        movq    mm4, MMWORD [wk(2)]     ; mm4=tmp13L
        movq    mm3, MMWORD [wk(3)]     ; mm3=tmp13H
        movq    mm0, MMWORD [wk(8)]     ; mm0=tmp0L
        movq    mm5, MMWORD [wk(9)]     ; mm5=tmp0H

        movq    mm1,mm4
        movq    mm2,mm3
        paddd   mm4,mm0                 ; mm4=data3L
        paddd   mm3,mm5                 ; mm3=data3H
        psubd   mm1,mm0                 ; mm1=data4L
        psubd   mm2,mm5                 ; mm2=data4H

        movq    mm0,[GOTOFF(ebx,PD_DESCALE_P2)] ; mm0=[PD_DESCALE_P2]

        paddd   mm4,mm0
        paddd   mm3,mm0
        psrad   mm4,DESCALE_P2
        psrad   mm3,DESCALE_P2
        paddd   mm1,mm0
        paddd   mm2,mm0
        psrad   mm1,DESCALE_P2
        psrad   mm2,DESCALE_P2

        movq      mm5,[GOTOFF(ebx,PB_CENTERJSAMP)]      ; mm5=[PB_CENTERJSAMP]

        packssdw  mm4,mm3               ; mm4=data3=(03 13 23 33)
        packssdw  mm1,mm2               ; mm1=data4=(04 14 24 34)

        movq      mm0, MMWORD [wk(0)]   ; mm0=(00 10 20 30 06 16 26 36)
        movq      mm3, MMWORD [wk(1)]   ; mm3=(01 11 21 31 07 17 27 37)

        packsswb  mm6,mm1               ; mm6=(02 12 22 32 04 14 24 34)
        packsswb  mm4,mm7               ; mm4=(03 13 23 33 05 15 25 35)

        paddb     mm0,mm5
        paddb     mm3,mm5
        paddb     mm6,mm5
        paddb     mm4,mm5

        movq      mm2,mm0               ; transpose coefficients(phase 1)
        punpcklbw mm0,mm3               ; mm0=(00 01 10 11 20 21 30 31)
        punpckhbw mm2,mm3               ; mm2=(06 07 16 17 26 27 36 37)
        movq      mm1,mm6               ; transpose coefficients(phase 1)
        punpcklbw mm6,mm4               ; mm6=(02 03 12 13 22 23 32 33)
        punpckhbw mm1,mm4               ; mm1=(04 05 14 15 24 25 34 35)

        movq      mm7,mm0               ; transpose coefficients(phase 2)
        punpcklwd mm0,mm6               ; mm0=(00 01 02 03 10 11 12 13)
        punpckhwd mm7,mm6               ; mm7=(20 21 22 23 30 31 32 33)
        movq      mm5,mm1               ; transpose coefficients(phase 2)
        punpcklwd mm1,mm2               ; mm1=(04 05 06 07 14 15 16 17)
        punpckhwd mm5,mm2               ; mm5=(24 25 26 27 34 35 36 37)

        movq      mm3,mm0               ; transpose coefficients(phase 3)
        punpckldq mm0,mm1               ; mm0=(00 01 02 03 04 05 06 07)
        punpckhdq mm3,mm1               ; mm3=(10 11 12 13 14 15 16 17)
        movq      mm4,mm7               ; transpose coefficients(phase 3)
        punpckldq mm7,mm5               ; mm7=(20 21 22 23 24 25 26 27)
        punpckhdq mm4,mm5               ; mm4=(30 31 32 33 34 35 36 37)

        pushpic ebx                     ; save GOT address

        mov     edx, JSAMPROW [edi+0*SIZEOF_JSAMPROW]
        mov     ebx, JSAMPROW [edi+1*SIZEOF_JSAMPROW]
        movq    MMWORD [edx+eax*SIZEOF_JSAMPLE], mm0
        movq    MMWORD [ebx+eax*SIZEOF_JSAMPLE], mm3
        mov     edx, JSAMPROW [edi+2*SIZEOF_JSAMPROW]
        mov     ebx, JSAMPROW [edi+3*SIZEOF_JSAMPROW]
        movq    MMWORD [edx+eax*SIZEOF_JSAMPLE], mm7
        movq    MMWORD [ebx+eax*SIZEOF_JSAMPLE], mm4

        poppic  ebx                     ; restore GOT address

        add     esi, byte 4*SIZEOF_JCOEF        ; wsptr
        add     edi, byte 4*SIZEOF_JSAMPROW
        dec     ecx                             ; ctr
        jnz     near .rowloop

        emms            ; empty MMX state

        pop     edi
        pop     esi
;       pop     edx             ; need not be preserved
;       pop     ecx             ; need not be preserved
        pop     ebx
        mov     esp,ebp         ; esp <- aligned ebp
        pop     esp             ; esp <- original ebp
        pop     ebp
        ret

; For some reason, the OS X linker does not honor the request to align the
; segment unless we do this.
        align   16